I am having the same problem with the Contact Us page. I am using WordPress 3.0.1 and wp mail SMPT. In the wp mail SMPT plugin I can send test emails and I am receiving email notifications of comments. So I think the plugin is working.

I tried Contact Form 7, which worked with wp_mail. When testing I was finding that our spam filter was catching incoming ‘contact us’ messages, whereas it wasn’t stopping general WordPress communications.

For the time being I am trying out the ‘contact us’ button from contactme.com. This has the advantage that now I have their email whitelisted, so that new contacts come into our email box.